The long-term objective is to provide a better understanding of tryptophan and lysine catabolism and of regulatory mechanisms in the pathway that may be important in normal and pathological functions in mammals. Changes of amino acid metabolism in Reyes' Syndrome will be determined in order to assess the role of disturbed tryptophan and lysine metabolism in causing the disorder. We will also attempt in studies of cell organelles, whole cells, and whole animals to determine whether the intracellular localizations of the degradative enzymes of these pathways may result in permeability barriers that regulate the pathways. An effect of Ca ions on Kynureninine amino transferase activity of isolated mitochondria will be further investigated as a possible regulatory factor in the pathways. Kynurenine aminotransferase, which is involved in both the tryptophan and lysine pathways, will be further purified and characterized.